Taliyah's W

Yeah, it makes sense that she should be able to throw herself over her own walls

I feel like that would make them a little too similar, as well as removing one of her actual decisions to make.

She doesn't actually like being super close to enemies. Medium range is preferred. Her W pushes enemies that get on top of her away. If she went along with it then it would defeat the point. Plus ya I think it would make her a bit too similar to Ziggs, especially with that Minefield E.

Designers said in live stream this is not because it would be unbalanceable, but because it promoted holding on to the ability and not using it in combos, something they did not want, they wanted her to use the spell in combat and as a part of her damage, not an escape route.

This is also why the ult does no damage as they wanted us to use it as a gapcloser/for powerful utility rather than saving it as something you can get some extra damage in you combo with.